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What GAO Found

The Internal Revenue Service (IRS) spends most of its enforcement resources on examinations. Correspondence exams of individual tax returns, which target fewer and simpler compliance issues, are significantly less costly on average than the broader and more complex field exams. GAO estimated that the average cost (including overhead) of correspondence exams opened in 2007 and 2008 was $274, compared to an average of $2,278 for field exams. IRS spent almost 20 percent of the $1.6 billion per year that it devoted to exams on returns from taxpayers with positive income of at least $200,000, even though such returns accounted for only 3 percent of the 136 million individual returns filed per year. (Positive income, a measure that IRS uses to classify returns for exam planning purposes, disregards losses that may offset this income).

GAO estimated that, for the 2 years of cases reviewed, correspondence exams were significantly more productive in terms of direct revenue produced per dollar of cost than field exams. Both types of exams of taxpayers with positive incomes of at least $200,000 were significantly more productive than exams of lower-income taxpayers.

GAO demonstrated how these estimates could be used to inform resource allocation decisions. For example, a hypothetical shift of a small share of resources (about $124 million) from exams of tax returns in less productive groups shown in the figure to exams in the more productive groups could have increased direct revenue by $1 billion over the $5.5 billion per year IRS actually collected (as long as the average ratio of direct revenue to cost for each category of returns did not change). These gains would recur annually, relative to the revenue that IRS would collect if it did not change its resource allocation. This particular resource shift would not reduce exam coverage rates significantly and, therefore, should have little, if any, negative effect on voluntary compliance.

Why GAO Did This Study

Heightened attention to federal deficits has increased pressure on IRS to reduce the tax gap--the difference between taxes owed and taxes paid on time--and better enforce taxpayer compliance. Resource limitations and concern over taxpayer burden, however, prevent IRS from auditing more than a small fraction of individual income tax returns filed. How IRS allocates these limited resources demands careful consideration.

As requested, this report (1) describes how IRS allocates resources across individual taxpayer compliance enforcement programs and across types of taxpayers within each program; (2) estimates the direct revenue return on investment for the individual taxpayer enforcement programs and the extent of variation across those programs and across types of taxpayers; and (3) determines the potential for gains from shifting resources from lower-yielding programs and types of taxpayers to higher-yielding ones.

What GAO Recommends

GAO recommends that IRS review disparities in the ratios of direct revenue yield to costs across different enforcement programs and across different groups of cases and consider this evidence as a potential basis for adjusting its allocation of enforcement resources each year. IRS agreed with the recommendations.

Recommendations for Executive Action

Status: Open

Priority recommendation

Comments: IRS agrees in principle to using ratios of direct revenue yield-to-cost to adjust its enforcement resource allocation, as GAO recommended in December 2012; however, IRS officials plan to wait until it has developed such ratios at the marginal level (e.g., for the last cases worked within specific categories of exams) before they make such adjustments. GAO maintains that IRS has a basis to adjust its allocation of enforcement resources each year and could improve resource allocation immediately (while it is still working to develop the marginal ratios) by using average yield-to-cost ratios for each category. IRS has developed a methodology for estimating marginal ratios for limited subsets of cases within their correspondence examination program. IRS officials are working to apply this methodology to other cases within that program; however, they expect this effort will be complex and time consuming and officials did not have a timeline for full implementation as of March 2017. If IRS does not take into account some measure of revenue yield per dollar of cost when making allocation decisions, it will miss an opportunity to collect significant amounts of additional revenue.

Recommendation: To better ensure that IRS's limited enforcement resources are allocated in a manner that maximizes the revenue yield of the income tax, subject to other important objectives of tax administration, such as minimizing compliance costs and ensuring equitable treatment across different groups of taxpayers, the Commissioner of Internal Revenue should review disparities in the ratios of direct revenue yield to costs across different enforcement programs and across different groups of cases within programs and determine whether this evidence provides a basis for adjusting IRS's allocation of enforcement resources each year. As part of this review, IRS should develop estimates of the marginal direct revenue and marginal direct cost within each enforcement program and each taxpayer group.

Agency Affected: Department of the Treasury: Internal Revenue Service

Status: Open

Comments: IRS has developed a methodology to estimate for each closed correspondence audit the total cost to IRS to identify, assess, and collect whatever direct revenue is collected from that audit. These estimated take into account the actual time applied in Examination and Appeals, as well as the job series and grades of the Exam and Appeals employees who handled each return. Collections cost do not vary significantly across the population of correspondence audits, so an average cost factor is used for that portion of the costs. IRS anticipates that expanding this estimation effort to other enforcement programs, such as field examination will require a much larger effort. As of December 2015, officials did not yet have a timeline for full implementation. If IRS does not take into account some measure of revenue yield per dollar of cost when making allocation decisions, it will miss an opportunity to collect significant amounts of additional revenue.

Recommendation: To better ensure that IRS's limited enforcement resources are allocated in a manner that maximizes the revenue yield of the income tax, subject to other important objectives of tax administration, such as minimizing compliance costs and ensuring equitable treatment across different groups of taxpayers, the Commissioner of Internal Revenue should review disparities in the ratios of direct revenue yield to costs across different enforcement programs and across different groups of cases within programs and determine whether this evidence provides a basis for adjusting IRS's allocation of enforcement resources each year. As part of this review, IRS should compile data on the amount of time that specific grades of examiners and downstream employees spend on specific categories of exams that can be identified in ERIS.

Agency Affected: Department of the Treasury: Internal Revenue Service

Status: Open

Comments: IRS has not yet found a way to use NRP data or other data sources to estimate the indirect effects of audits. While they continue to explore alternative ways to estimate these effects, they expect to continue to account for these effects subjectively as they develop their enforcement resource allocation plans. As of December 2015, officials did not yet have a timeline for full implementation. If IRS does not take into account some measure of revenue yield per dollar of cost when making allocation decisions, it will miss an opportunity to collect significant amounts of additional revenue.

Recommendation: To better ensure that IRS's limited enforcement resources are allocated in a manner that maximizes the revenue yield of the income tax, subject to other important objectives of tax administration, such as minimizing compliance costs and ensuring equitable treatment across different groups of taxpayers, the Commissioner of Internal Revenue should review disparities in the ratios of direct revenue yield to costs across different enforcement programs and across different groups of cases within programs and determine whether this evidence provides a basis for adjusting IRS's allocation of enforcement resources each year.As part of this review, IRS should explore the potential of estimating the marginal influence of enforcement activity on voluntary compliance, potentially taking advantage of new NRP data.